A conventional bidirectional DC/DC converter performs bidirectional power transmission between a first DC power supply and a second DC power supply, and includes: a transformer; a first converter unit which has a plurality of semiconductor switching elements, is connected between the first DC power supply and a first winding of the transformer, and performs power conversion between DC and AC; a second converter unit which has a plurality of semiconductor switching elements, is connected between the second DC power supply and a second winding of the transformer, and performs power conversion between DC and AC; and a control circuit which controls the semiconductor switching elements in the first and second converter units. The first and second converter units have capacitors connected in parallel to the respective semiconductor switching elements, and first and second reactors connected to AC input/output lines. In power transmission from the first DC power supply to the second DC power supply, the control circuit performs control so that the semiconductor switching elements in the first converter unit perform zero voltage switching, using the first reactor, and when voltage of the second DC power supply is higher than voltage generated at the second winding of the transformer, the control circuit performs control so that the second converter unit performs step-up operation, using the second reactor. In power transmission from the second DC power supply to the first DC power supply, the control circuit performs control so that the semiconductor switching elements in the second converter unit perform zero voltage switching, using the second reactor, and when voltage of the first DC power supply is higher than voltage generated at the first winding of the transformer, the control circuit performs control so that the first converter unit performs step-up operation, using the first reactor (see, for example, Patent Document 1).